Electric furnace



Sept. 13, 1927.

D. CROESE ELECTRIC FURNACE Filed Dec. 1, 1926 2 Sheets-Sheet 1 i'L'f T792 1 I 4% w N I L.

, If 4 m 1 4 gntghkkgj 13. 1927. D CROESE 1,642,359

ELECTRIC FURNACE vFiledDec 1, 1925 2 Sheets-Sheet 2 i 4 w I: 22 L 25 20Patented Sept 13, 1927 UNITEi) STATES PATENT orrica.

DIRK CROESE, OE LONDON, ENGLAND.

' ELECTRIC, FURNACE.

Application filed December 1, 1926, Serial No. 152,020, and in GreatBritain August, 1995.

This invention relates to the manufacture of metals and alloys fromfinely divided mineral substances and has particular reference to theproduction or. reduction of metals from their ores in the electricfurnace.

' The object of the present invention is to of the furnace.-

provide an improved method of and means Figure 2 is a vertical sectionalelevation forthe electric treatment of metal bearing substances a finelwhich will ehable SllCl substances as ironsand to be treated for theproduction of metal on a commercial scale.

A ccording.to the invention a process is provided for the reduction ofmetal or allo from finely divided ores such as ironsan such processconsisting in the removal of impurities, in causing the concentratedmaterial to fallby gravity through a furnace divided into chambers inwhich the falling material is first preheated and is then caused to passsuccessively freely through a number of electric arcs undernon-oxidizing conditions for the purpose of melting and reduction and inwhich further heat treatment is finally applied to facilitate separationof metal from slag.

The invention may be carried into effect in an electric furnacecomprising a preheating chamber and a series of arc chambers throughwhich the material to be treated falls freely b gravity, -each arcchamber being provide with means to break up the fallin material anddeflect it on to the next are 0 the series. The deflecting meanspreferably comprise a double cone of carbon dis d near the base ofthearc chamber WhlCll tapers towards an outlet at its lower endand atthe base of the series of chamhers is disposed a heated crucible adaptedto be tilted relatively to the upper part of the furnace or retort forthe purpose of discharging molten metal or slag. Both retort andcrucible are provided with means for preventing ingress of air duringnormal operation and whilst discharging. and in order to render thereduction to metal as complete as possible thecrucible may be heated byelectric arcs in con'unction with a. rotary. or otherwise mova lemagnetic field to ensure that the action of the arcs is made effectivein every. part of the crucible. Alternatively, the ases evolved by thereaction which takes ace in the furnace and which are normal ydischarged to at- .mosphere or employed for power production may beutilized for'heating the crucible.

divided state and the furnace walls to Reference will now be madeto theaccompanyiug drawin of example an el the invention into effect and inwhich-:-

Figure 1 is a vertical sectional elevation of a tilting crucible adaptedto be employed in conjunction with the furnace shown in Fi re 1 and thecrucible shown in Figure 2.

which illustrate by way" ectric furnace for carrying The electricfurnace 1 is of tubular form and com rises at the topa feed hopper 2from the use of which a conveyor- 3 removes the material to be treatedto an inlet4 disposed centrally at the top of the furnace l, theconveyor 3 and inlet 4 being. suitably housed within a casing 5toprevent entry of air at the top of the furnace and avoid oxidization ofthe material under treatment The incoming material which falls from theInlet passage 4 meets a conical bafiie 6, the object of which is tobreak up and distribute the incoming finely divided material towardsnevent it assing too rapidly through the urnace and thus partiallyescaping treatment by the electric area as hereinafter described. Theconical baflle 6 is disposed ccntrall within a pr'eheating chamber 7such baiile forming part of a double conical element supported on arms 8projecting inwardly from a lining element 9 which forms the base of thepreheating chamber and which ta rs internally towards an outlet 10 atits hiss. The elements 6, 8 and 9 are formed from graphite or likematerial and are mounted in a lining of firebrick or like material 11which forms the wall of the furnace and is enclosed by an outersheathing of metal.

The upper or pre-heating'chamber 7 of a the furnace communicates tnroughthe outtheir height; witli 2. number of ins ection doors fitted overopenings la'and pre erably provided with transparent portions forsighting whilst each electrode chamber 12 is provided with a cleaningdoor fitted over an opening 15, the dooraof openings 14 and 15 beingluted with fire clay or hermetically sealed 1n some'other manner priorto the furnace being set in operation.

The lowermost electrode chamber 12 is notprovided with a tapered. basebut communicates directly with a crucible 16 disposed immediatelybelow'the base of the furnace, this crucible being arranged so that themetal can separate from the slag and two or more separate outlets 17 and18 are provided to enable the molten material to be withdrawn, theseopenings being normally closed by counterbalanced sliding doors 19. Theupper ortion 20 of the crucible is of the same iameter as the lowermostelectrode chamber 12 and the engagement between the two is by means of aair of curved co-operatingsurfaces 21 WlllCl'l permit the curcible to betilted for the purpose of discharging. Whilst the furnace is inoperation the base of the lowermost electrode chamber and the portion 20of the crucible are coupled by means of a sleeve 22 which can be raisedwhen it is desired to tilt the crucible. The crucible 16 is providedwith openings 23 at each side which enable three pairs of electrodes tobe mounted within the crucible, this number being variable accordin torequirements in order to impart fina treatment to the molten materialwhich collects in the crucible. This final treatment may be conductedindependently of the vertical furnace and dampers 24 and 25 slidablymounted in the base of the lowermost electrode chamber and in theportion 20 of the crucible respectively may be provided to cut offcommunication between the vertical electrode chambers 12 and thecrucible 16 when such final treatment is in progress. Beneath thecrucible a framework 26 is provided to permit an eleetromagnet beinmounted at this point for the purpose 0 attracting the arcs towards thesurface of the molten material collectin on the hearth 27 within thecrucible and his electromag net may be so arranged as to produce arotating or otherwise movable magnetic field in order to ensure that theheating efiect of the arcs is carried to every part of the materialcollecting in the crucible.

The tilting mechanism for the crucible comprises a hand wheel 28 (seeFigure 3) mounted on a spindle 29 and operating a worm 3O meshing with aworm wheel 31 with which a spur wheel 32 is co-axially mounted. The spurwheel 32 engages a toothed sector 33 fixed to the side of the crucible16 and provided with a plane surface 34 struck from the same centre asthe 3 tion of metal.

toothed sector 33 but engaged by friction rollers 35 for the pur se ofbraki the movement of the cruci le when it is ing moved towards thedischarging position.

The furnace is provided with outlets 36 for waste gases such outletscommunicating with chimneys 37 as shown in Figure 1.

The ore to be treated is reduced to a finely divided condition bygrinding or crushin and if irousand is the substance to be treat it issubject to a preliminar operation to remove -impurities prefera ly. bypassa through a magnetic separating device. TE: process is theneontinued in the furnace above described in the following manner Thefinely divided metal bearing material falls in a continuous stream fromthe inlet 4 into the furnace 1, the internal arrangement of whichensures that the falli particles are exposed to the heat generate by thearcs at the electrodes 13 for the len of time necessary to effectcomplete meltin and reduction of all the material passe through thefurnace. Whereas the melting point of titaniferous ironsand for exampleis about 1500 C. and the temperature of the electric arc is over 3000 C.it follows thatwhen ironsand is treated these particles will becompletely melted and reduced by passage throu h the arcs, thearrangement of which in addition to the construction of the furnacepreclude the formation of a fused mass of material which has beenan'obstacle hitherto to the employment of the electric furnace intreating ironsand for the produc- It is to be noted that the uppermostchamber 7 contains no electrodes but becomes heated to the degreenecessary to preheat the falling material by part of the ases whichascend from the reaction which takes place in the electrode chambers.The material resulting from the treatment in the furnace 1 collects inthe crucible 16 where waste substances suchas silica, lime and sulphuror lect. in a layer a ove the layers of titanium and iron or steel.The-waste gases from the reactiontaking place'within the furnace passupwardly through the-descending material and are withdrawn at a ointbelow the preheating chamber throu g the outlets 36 and chimneys 37,part of t ese gases,'however, circulating through the chamber 7 beforeescaping.

In an alternative arrangement the gas outlet conduit may pass to thebase of the furnace where a raft of air is introduced and the gas burntaround the crucible 16 to maintain the contents thereof in a moltencondition, this arrangement being employed as an alternative or inaddition to the use of electrodes within the crucibleas above de'scribedh If desired resistance heating may also be employed in additionto or place of the aforesaid methods of heating the phosphorus compoundscol- I gas may be passed into storage for use in operating a prime moverand an electricity generating plant.

The preheating chamber 7 may be heated electrically by elements disposedexternally or interiially thereof.

The conical elements 6 are preferably supported by four members 8arranged at ri ht angles one to the other so that the falling materialis, alternatively diverted into four streams and re-united in theontletpassages 10 so that a thorough separation of the ma terial is obtainedas it ails through each stage of the furnace ensuring that everyparticle-receives the full influence of the electric arcs. The conedbailles also have the efl'ect of preventing clogging of the material andalso of preventing the material passing too ra i'dly through thefurnace.

en ironsand or other material containing or consisting of metallic oxideis under treatment it.may be mixed with a quantity of.coke, an hrac te,-or other reducing agent before it is introduced to' the feed hopper 2 orsuch reducing agent may be introduced to the crucible 16.

"The treatment of ironsand by the process and in the furnace abovedescribed enables pure metal to be withdrawn from the crucile-16 throughone of its outlets, and titanium slag at the other outlet, the metalbeing a titanium steel alloy in which the percentage of'titanium variesaccording to the length of time the treated material is maintained in amolten condition in the crucible. been found that some of the titaniumalways goes into the slag which has thus various industrialapplicatiousjbut by continued heating the titanium contents of the alloycan be reduced to less than 1 per cent producing the best qualitytitanium steel. if desired the process above described may be carriedout in an inert atmosphere. and for this purpose an inert gas would heintroduced near the base of the lowermost electrode chamber 12.

The invention is not liu'iited to any particular disposition of theelectrodes within each chamber 12 as the electrodes in one chamber maybe disposed at a i'litlerent angle relatively to those in the chamberabove or below or several pairs of electrodes may be dis osed in eachchamber.

laims: 1. An electric furnace for the. production of metals from theirores comprising a ver- It has each chamber, a crucible in which thepro-- ducts from the retort collect, means for heating said crucibleand-means for preventingingress of air to said crucible and retort.

2. An electric furnace for the production of metals from their orescompris' a vertical retortidivided into separate c ambers by means of anumber of double conical carbon baflles each of which cooperates with adownwardly tapering, throat of'similar material, the upper chamberserving for preheating a stream of freely falling material and the otherchambers as are chambers the base of said retort discharging into aheated crucible adapted to be tilt for the purpose of discharging moltenme al and slag therefrom.

3. -An electric arc furnace for treating finely d vided ores comprisinga preheatin chamber, a series of arc chambers disposed verticallybeneath said preheating chamber, a base to each arc chamber comprisingan inwardly tapering portion having inwardly directed members whichsupport a double conical ballle concentrically with the chamber and forma number of passages through which the material deflected by the bafileis caused to pass, means for feeding material to be treated to the topof said reheatin chamber so as to fall by gravity t rough al of saidchambers. and a heated crucible adapted to receive the material treatedin said chambers.

4. An electric arc furnace for treating finely divided ores comprising apreheatin chamber, a series of arc chambers dispose vertically beneathsaid preheatin chamber, means for feeding material to said reheatingchamber in such a manner that t e'operation is carried out undernon-oxidizing conditions, a base to each arc chamber comprising aninwardly tapering portion having inwardly directed members which sup rt8. double conical nntlle concentrically with the arc chamber and form anumber of passages through which the. material deflected by the bafileis caused to pass by gravity to the next succeeding chamber. a heatedcrucible at the base of said furnace, means for shutting off thecrucible from the furnace, and means for tilting the crucible fordischarging purposes.

In witness whereof I affix I11? si nature.

DIR cfionsa.

